Lhx4 surpasses its paralog Lhx3 in promoting the differentiation of spinal V2a interneurons.

Paralog factors are considered to ensure the robustness of biological processes by providing redundant activity in cells where they are co-expressed. However, the specific contribution of each factor is frequently underestimated. In the developing spinal cord, multiple families of transcription factors successively contribute to differentiate an initially homogenous population of neural progenitors into a myriad of neuronal subsets with distinct molecular, morphological, and functional characteristics. The LIM-homeodomain transcription factors Lhx3, Lhx4, Isl1 and Isl2 promote the segregation and differentiation of spinal motor neurons and V2 interneurons. Based on their high sequence identity and their similar distribution, the Lhx3 and Lhx4 paralogs are considered to contribute similarly to these processes. However, the specific contribution of Lhx4 has never been studied. Here, we provide evidence that Lhx3 and Lhx4 are present in the same cell populations during spinal cord development. Similarly to Lhx3, Lhx4 can form multiproteic complexes with Isl1 or Isl2 and the nuclear LIM interactor NLI. Lhx4 can stimulate a V2-specific enhancer more efficiently than Lhx3 and surpasses Lhx3 in promoting the differentiation of V2a interneurons in chicken embryo electroporation experiments. Finally, Lhx4 inactivation in mice results in alterations of differentiation of the V2a subpopulation, but not of motor neuron production, suggesting that Lhx4 plays unique roles in V2a differentiation that are not compensated by the presence of Lhx3. Thus, Lhx4 could be the major LIM-HD factor involved in V2a interneuron differentiation during spinal cord development and should be considered for in vitro differentiation of spinal neuronal populations.

Effect of a Wearable Device-Based Physical Activity Intervention in North Korean Refugees: Pilot Randomized Controlled Trial.

BACKGROUND: Effective health interventions for North Korean refugees vulnerable to metabolic disorders are currently unelucidated. OBJECTIVE: This study aimed to evaluate the effects of digital health interventions in North Korean refugees using a wearable activity tracker (Fitbit device). METHODS: We conducted a prospective, randomized, open-label study on North Korean refugees aged 19-59 years between June 2020 and October 2021 with a 12-week follow-up period. The participants were randomly assigned to either an intervention group or a control group in a 1:1 ratio. The intervention group received individualized health counseling based on Fitbit data every 4 weeks, whereas the control group wore the Fitbit device but did not receive individualized counseling. The primary and secondary outcomes were the change in the mean daily step count and changes in the metabolic parameters, respectively. RESULTS: The trial was completed by 52 North Korean refugees, of whom 27 and 25 were in the intervention and control groups, respectively. The mean age was 43 (SD 10) years, and 41 (78.8%) participants were women. Most participants (44/52, 95.7%) had a low socioeconomic status. After the intervention, the daily step count in the intervention group increased, whereas that in the control group decreased. However, there were no significant differences between the 2 groups (+83 and -521 steps in the intervention and control groups, respectively; P=.500). The effects of the intervention were more prominent in the participants with a lower-than-average daily step count at baseline (<11,667 steps/day). After the 12-week study period, 85.7% (12/14) and 46.7% (7/15) of the participants in the intervention and control groups, respectively, had an increased daily step count (P=.05). The intervention prevented the worsening of the metabolic parameters, including BMI, waist circumference, fasting blood glucose level, and glycated hemoglobin level, during the study period. CONCLUSIONS: The wearable device-based physical activity intervention did not significantly increase the average daily step count in the North Korean refugees in this study. However, the intervention was effective among the North Korean refugees with a lower-than-average daily step count; therefore, a large-scale, long-term study of this intervention type in an underserved population is warranted. TRIAL REGISTRATION: Clinical Research Information Service KCT0007999; https://cris.nih.go.kr/cris/search/detailSearch.do/23622.

Comparison of the McGRATHTM Video Laryngoscope and Macintosh Laryngoscope for Orotracheal Intubation in a Simulated Difficult Airway Scenario: An Open-Label, Randomized Clinical Trial.

Background and Objectives: Difficult intubation, which may be encountered unexpectedly during anesthesia, can increase patients' morbidity and mortality. The McGRATH video laryngoscope is known to provide improved laryngeal visibility in patients with difficult or normal airways. The purpose of this study was to evaluate the efficacy of the McGRATH video laryngoscope for orotracheal intubation compared with that of conventional Macintosh laryngoscopes in simulated difficult airway scenarios. Materials and Methods: In this randomized controlled trial, patients who were scheduled for surgery under general anesthesia requiring orotracheal intubation were assigned to the Macintosh laryngoscope (n = 50) or McGRATH video laryngoscope (n = 45) groups. In this study, to create a simulated difficult airway condition, the subjects performed manual in-line stabilization and applied a soft cervical collar. The primary outcome was the rate of successful intubation within 30 s. The time required for an intubation, glottis grade, intubation difficulty scale (IDS score), the subjective ease of intubation, and optimal external laryngeal manipulation (OLEM) were evaluated. In addition, complications caused by each blade were investigated. Results: The intubation success rate within 30 s was not significantly different between the two groups (44 (88.0%) vs. 36 (80.0%), p = 0.286). The glottic grade was better in the McGRATH group than in the Macintosh group (p = 0.029), but neither the intubation time (26.3 ± 8.2 s vs. 24.2 ± 5.0 s, p = 0.134) nor the rates of oral bleeding (2 (4.0%) vs. 0 (0.0%)) and tooth injury (0 (0.0%) vs. 1 (2.2%)) were significantly different between the two groups. Conclusions: The use of the McGRATH video laryngoscope did not improve the intubation success rate or shorten the intubation time. However, the McGRATH video laryngoscope provided a better glottis view than the conventional Macintosh laryngoscope in patients with a simulated difficult airway.

Evaluation of Atopic Dermatitis Improvement Caused by Low-Level, Low-Frequency Pulsed Electromagnetic Fields.

This study aimed to evaluate the effectiveness of using low-level, low-frequency pulsed electromagnetic field (LLLF_PEMF) stimulation to improve atopic dermatitis induced by 2,4-dinitrochlorobenzene (DNCB). Twenty 6-week-old hairless mice were randomly divided into Normal (n = 5), PEMF 15 Hz (n = 5), PEMF 75 Hz (n = 5), and Sham (n = 5) groups. Following the onset of atopic dermatitis symptoms, PEMF groups (15 and 75 Hz) were stimulated with LLLF_PEMF (15 mT) for 8 h per day for 1 week. Sensory evaluation analysis revealed a significant difference between the PEMF 15 Hz group and Sham group (P < 0.05), but these differences were not visually obvious. While both the PEMF and Sham groups had atopic dermatitis lesions, lesion size was significantly smaller in the two PEMF groups than in the Sham group (P < 0.001). Additionally, changes in epithelial thickness because of skin inflammation significantly decreased for both PEMF groups, compared with the Sham group (P < 0.001). In conclusion, these results suggest that PEMF stimulation in vivo triggers electro-chemical reactions that affect immune response. © 2022 Bioelectromagnetics Society.

Vsx1 and Chx10 paralogs sequentially secure V2 interneuron identity during spinal cord development.

Paralog factors are usually described as consolidating biological systems by displaying redundant functionality in the same cells. Here, we report that paralogs can also cooperate in distinct cell populations at successive stages of differentiation. In mouse embryonic spinal cord, motor neurons and V2 interneurons differentiate from adjacent progenitor domains that share identical developmental determinants. Therefore, additional strategies secure respective cell fate. In particular, Hb9 promotes motor neuron identity while inhibiting V2 differentiation, whereas Chx10 stimulates V2a differentiation while repressing motor neuron fate. However, Chx10 is not present at the onset of V2 differentiation and in other V2 populations. In the present study, we show that Vsx1, the single paralog of Chx10, which is produced earlier than Chx10 in V2 precursors, can inhibit motor neuron differentiation and promote V2 interneuron production. However, the single absence of Vsx1 does not impact on V2 fate consolidation, suggesting that lack of Vsx1 may be compensated by other factors. Nevertheless, Vsx1 cooperates with Chx10 to prevent motor neuron differentiation in early V2 precursors although these two paralog factors are not produced in the same cells. Hence, this study uncovers an original situation, namely labor division, wherein paralog genes cooperate at successive steps of neuronal development.

A Case of Eosinophilic Pustular Folliculitis Associated With Herpes Zoster.

ABSTRACT: Patients with eosinophilic pustular folliculitis (EPF), a sterile eosinophilic infiltration of hair follicles, often present with papulopustules that tend to form annular plaques. Histopathologic examination revealed eosinophilic infiltration around the pilosebaceous units and eosinophilic microabscess formation. Although the pathogenesis of EPF is unknown, T-helper type 2 immune responses were suggested to be important based on their stimulating effect on the sebaceous glands. Here, we report the first case of EPF associated with herpes zoster, indicating that herpes zoster and EPF are correlated with T-helper type 2 immune responses.

UBE3A Suppresses Overnutrition-Induced Expression of the Steatosis Target Genes of MLL4 by Degrading MLL4.

Regulation of the protein stability of epigenetic regulators remains ill-defined despite its potential applicability in epigenetic therapies. The histone H3-lysine 4-methyltransferase MLL4 is an epigenetic transcriptional coactivator that directs overnutrition-induced obesity and fatty liver formation, and Mll4+/- mice are resistant to both. Here we show that the E3 ubiquitin ligase UBE3A targets MLL4 for degradation, thereby suppressing high-fat diet (HFD)-induced expression of the hepatic steatosis target genes of MLL4. In contrast to Mll4+/- mice, Ube3a+/- mice are hypersensitive to HFD-induced obesity and fatty liver development. Ube3a+/-;Mll4+/- mice lose this hypersensitivity, supporting roles of increased MLL4 levels in both phenotypes of Ube3a+/- mice. Correspondingly, our comparative studies with wild-type, Ube3a+/- and Ube3a-/- and UBE3A-overexpressing transgenic mouse livers demonstrate an inverse correlation of UBE3A protein levels with MLL4 protein levels, expression of the steatosis target genes of MLL4, and their decoration by H3-lysine 4-monomethylation, a surrogate marker for the epigenetic action of MLL4. Conclusion: UBE3A indirectly exerts an epigenetic regulation of obesity and steatosis by degrading MLL4. This UBE3A-MLL4 regulatory axis provides a potential therapeutic venue for treating various MLL4-directed pathogeneses, including obesity and hepatic steatosis.

The LIM-homeobox transcription factor Isl1 plays crucial roles in the development of multiple arcuate nucleus neurons.

Neurons in the hypothalamic arcuate nucleus relay and translate important cues from the periphery into the central nervous system. However, the gene regulatory program directing their development remains poorly understood. Here, we report that the LIM-homeodomain transcription factor Isl1 is expressed in several subpopulations of developing arcuate neurons and plays crucial roles in their fate specification. Mice with conditional deletion of the Isl1 gene in developing hypothalamus display severe deficits in both feeding and linear growth. Consistent with these results, their arcuate nucleus fails to express key fate markers of Isl1-expressing neurons that regulate feeding and growth. These include the orexigenic neuropeptides AgRP and NPY for specifying AgRP-neurons, the anorexigenic neuropeptide αMSH for POMC-neurons, and two growth-stimulatory peptides, growth hormone-releasing hormone (GHRH) for GHRH-neurons and somatostatin (Sst) for Sst-neurons. Finally, we show that Isl1 directly enhances the expression of AgRP by cooperating with the key orexigenic transcription factors glucocorticoid receptor and brain-specific homeobox factor. Our results identify Isl1 as a crucial transcription factor that plays essential roles in the gene regulatory program directing development of multiple arcuate neuronal subpopulations.

Single-stranded DNA binding proteins are required for LIM complexes to induce transcriptionally active chromatin and specify spinal neuronal identities.

LIM homeodomain factors regulate the development of many cell types. However, transcriptional coactivators that mediate their developmental function remain poorly defined. To address these, we examined how two related NLI-dependent LIM complexes, which govern the development of spinal motor neurons and V2a interneurons, activate the transcription in the embryonic spinal cord. We found that single-stranded DNA-binding proteins are recruited to these LIM complexes via NLI, and enhance their transcriptional activation potential. Ssdp1 and Ssdp2 (Ssdp1/2) are highly expressed in the neural tube and promote motor neuron differentiation in the embryonic spinal cord and P19 stem cells. Inhibition of Ssdp1/2 activity in mouse and chick embryos suppresses the generation of motor neurons and V2a interneurons. Furthermore, Ssdp1/2 recruit histone-modifying enzymes to the motor neuron-specifying LIM complex and trigger acetylation and lysine 4 trimethylation of histone H3, which are well-established chromatin marks for active transcription. Our results suggest that Ssdp1/2 function as crucial transcriptional coactivators for LIM complexes to specify spinal neuronal identities during development.

Can Nutritional Status Predict Overall Survival in Patients with Advanced Non-Small Cell Lung Cancer?

Medical records of patients with advanced non-small cell lung cancer (NSCLC) were retrospectively reviewed to examine the prognostic impact of nutritional status on survival. Age, sex, body mass index (BMI), Eastern Cooperative Oncology Group Performance Status (ECOG-PS), histologic tumor type, pulmonary comorbidities, white blood cell (WBC) count, C-reactive protein (CRP) level, and prognostic nutritional index (PNI) were assessed. Overall survival was calculated using Kaplan-Meier analysis and compared using log-rank testing. Univariate and multivariate Cox regression model analyses were used to evaluate prognostic impact. Of the 183 enrolled patients, 166 had stage IV NSCLC; 70 had ECOG-PS scores of 2; and 129 had undergone prior anticancer therapy. Age ≥ 65 years, male sex, smoking, BMI < 21 kg/m2, ECOG-PS score of 2, WBC count > 11,000 cells/µL, CRP level > 1.0 mg/dL, and PNI ≤46.1 were associated with poor overall survival. Multivariate analysis revealed that BMI ≥ 21 kg/m2 (hazard ratio [HR], 0.64) and PNI > 46.1 (HR, 0.65) were associated with prolonged survival, while age ≥ 65 years (HR, 1.48) and CRP level > 1.0 mg/dL (HR, 1.82) were associated with poor survival. In conclusion, BMI and PNI, as indicators of nutritional status, were significant independent prognostic factors of survival.

A case of multinucleate cell angiohistiocytoma in a 14-year-old boy showing two different clinical and histopathological findings.

Multinucleate cell angiohistiocytoma (MCAH) is a rare cutaneous disease entity characterized by multiple red-to-brown or violaceous papules usually located on the acral regions, such as the face and the distal arms and legs. It affects elderly women more than men and rarely occurs at a young age. The exact pathogenic mechanism of MCAH is not yet clearly understood. We report an exceptionally rare case of a 14-year-old boy who presented with multiple asymptomatic erythematous papules and a single flat brownish plaque on the left chest. The brownish plaque lesion histologically showed proliferation of dilated small vessels in the upper-mid dermis and numerous oddly shaped multinucleate cells intermingled with lymphocytes and macrophages. The erythematous papules also showed dilated small vessels in the upper-mid dermis and multiple interstitial histiocytic infiltrations, but no multinucleate cells were detected. In immunohistochemistry studies, CD68 and vimentin staining were positive for both specimens. Based on the clinicopathological findings and immunohistochemistry studies, MCAH was diagnosed. To the best of our knowledge, this is the first case report of MCAH occurring in young age and showing two different clinical and histological phases at the same time.

Significance of serum ferritin as a prognostic factor in advanced hepatobiliary cancer patients treated with Korean medicine: a retrospective cohort study.

BACKGROUND: Advanced hepatobiliary cancers are highly lethal cancers that require precise prediction in clinical practice. Serum ferritin level increases in malignancy and high serum ferritin level is associated with poor survival in various cancers. This study aimed to identify whether serum ferritin could independently predict the overall survival (OS) of patients with advanced hepatobiliary cancers. METHODS: The retrospective cohort study was performed by reviewing medical records of patients with advanced hepatobiliary cancers from June 2006 to September 2016. The demographic and clinicopathological characteristics as well as the biochemical markers were evaluated at the initiation of Korean medicine (KM) treatment. The OS was calculated using Kaplan-Meier estimates. The Cox proportional hazard model was used to identify the independent prognostic significance of serum ferritin for survival. RESULTS: The median OS of all subjects was 5.1 months (range, 0.5-114.9 months). The median OS of group with low ferritin levels and that with high ferritin levels was 7.5 months (range, 0.7-114.9 months) and 2.8 months (range, 0.5-22.8 months), respectively (P < 0.001). The results of the univariate analysis showed that the Eastern Cooperative Oncology Group Performance Status (ECOG-PS) (P = 0.002), tumor type (P = 0.001), prior treatment (P = 0.023), serum ferritin (P < 0.001), hemoglobin (P = 0.002), total bilirubin (P = 0.002), gamma-glutamyl transpeptidase (P = 0.007), albumin (P = 0.013), white blood cell (P = 0.002), and C-reactive protein (CRP) (P < 0.001) were significant factors for the patients' survival outcome. On multivariate analysis controlling confounding factors, ferritin (P = 0.041), CRP (P = 0.010), ECOG-PS (P = 0.010), and tumor type (P = 0.018) were identified as independent prognostic factors for survival. CONCLUSIONS: These results indicate that serum ferritin is a valid clinical biochemical marker to predict survival of patients with advanced hepatobiliary cancers.

cAMP/PKA signalling reinforces the LATS-YAP pathway to fully suppress YAP in response to actin cytoskeletal changes.

Actin cytoskeletal damage induces inactivation of the oncoprotein YAP (Yes-associated protein). It is known that the serine/threonine kinase LATS (large tumour suppressor) inactivates YAP by phosphorylating its Ser127 and Ser381 residues. However, the events downstream of actin cytoskeletal changes that are involved in the regulation of the LATS-YAP pathway and the mechanism by which LATS differentially phosphorylates YAP on Ser127 and Ser381 in vivo have remained elusive. Here, we show that cyclic AMP (cAMP)-dependent protein kinase (PKA) phosphorylates LATS and thereby enhances its activity sufficiently to phosphorylate YAP on Ser381. We also found that PKA activity is involved in all contexts previously reported to trigger the LATS-YAP pathway, including actin cytoskeletal damage, G-protein-coupled receptor activation, and engagement of the Hippo pathway. Inhibition of PKA and overexpression of YAP cooperate to transform normal cells and amplify neural progenitor pools in developing chick embryos. We also implicate neurofibromin 2 as an AKAP (A-kinase-anchoring protein) scaffold protein that facilitates the function of the cAMP/PKA-LATS-YAP pathway. Our study thus incorporates PKA as novel component of the Hippo pathway.

Isl1 directly controls a cholinergic neuronal identity in the developing forebrain and spinal cord by forming cell type-specific complexes.

The establishment of correct neurotransmitter characteristics is an essential step of neuronal fate specification in CNS development. However, very little is known about how a battery of genes involved in the determination of a specific type of chemical-driven neurotransmission is coordinately regulated during vertebrate development. Here, we investigated the gene regulatory networks that specify the cholinergic neuronal fates in the spinal cord and forebrain, specifically, spinal motor neurons (MNs) and forebrain cholinergic neurons (FCNs). Conditional inactivation of Isl1, a LIM homeodomain factor expressed in both differentiating MNs and FCNs, led to a drastic loss of cholinergic neurons in the developing spinal cord and forebrain. We found that Isl1 forms two related, but distinct types of complexes, the Isl1-Lhx3-hexamer in MNs and the Isl1-Lhx8-hexamer in FCNs. Interestingly, our genome-wide ChIP-seq analysis revealed that the Isl1-Lhx3-hexamer binds to a suite of cholinergic pathway genes encoding the core constituents of the cholinergic neurotransmission system, such as acetylcholine synthesizing enzymes and transporters. Consistently, the Isl1-Lhx3-hexamer directly coordinated upregulation of cholinergic pathways genes in embryonic spinal cord. Similarly, in the developing forebrain, the Isl1-Lhx8-hexamer was recruited to the cholinergic gene battery and promoted cholinergic gene expression. Furthermore, the expression of the Isl1-Lhx8-complex enabled the acquisition of cholinergic fate in embryonic stem cell-derived neurons. Together, our studies show a shared molecular mechanism that determines the cholinergic neuronal fate in the spinal cord and forebrain, and uncover an important gene regulatory mechanism that directs a specific neurotransmitter identity in vertebrate CNS development.

Effect of TV food advertising restriction on food environment for children in South Korea.

Summary: This study attempted to determine the effects of restrictions on television (TV) food advertising on children's food environments in South Korea. It examined changes that occurred in the marketing mix of food companies following enactment of those restrictions. An on-line survey was conducted with marketers or R&D managers of 108 food companies. A questionnaire was used to inquire about changes that occurred in Product, Place, Price and Promotion as a result of the restrictions placed on TV food advertising. Analysis was performed on the data collected from the responding 63 food companies (58.3%). The results of their answers showed that among the four marketing mix components the restrictions exerted relatively stronger effects on Product. Effects were stronger on companies that produced foods within the product categories of Energy-Dense and Nutrient-Poor foods (EDNP companies) in comparison with companies that did not (non-EDNP companies). The restrictions exerted positive effects on EDNP companies with respect to compliance with labeling requirements and reinforcement of nutritional contents examination, as well as changes to products such as reducing unhealthy ingredients and fortifying nutrients. Overall, the results revealed the possibility that restrictions on TV food advertising could improve children's food environments by encouraging EDNP companies to make favorable product changes. On the one hand, the results also found that some food companies attempted to bypass the regulations by changing marketing channels from TV to others and by reducing product serving sizes. Thus, future measures should be implemented to prevent food companies from bypassing regulations and to control children's exposure to marketing channels other than TV.

Crucial roles of mixed-lineage leukemia 3 and 4 as epigenetic switches of the hepatic circadian clock controlling bile acid homeostasis in mice.

UNLABELLED: The histone H3-lysine-4 methyltransferase mixed-lineage leukemia 3 (MLL3) and its closest homolog, MLL4 (aka KMT2D), belong to two homologous transcriptional coactivator complexes, named MLL3 and MLL4 complexes, respectively. MLL3 plays crucial roles in multiple metabolic processes. However, the physiological roles of MLL4 in metabolism and the relationship between MLL3 and MLL4 in metabolic gene regulation are unclear. To address these issues, we analyzed the phenotypes of newly generated MLL4 mutant mice, along with MLL3 mutant and MLL3;MLL4 compound mutant mice. We also performed comparative genome-wide transcriptome analyses in livers of MLL3, MLL4, and MLL3;MLL4 mutant mice. These analyses revealed that MLL3 and MLL4 complexes are key epigenetic regulators of common metabolic processes and the hepatic circadian clock. Subsequent mechanistic analyses uncovered that MLL3/4 complexes function as pivotal coactivators of the circadian transcription factors (TFs), retinoid-related orphan receptor (ROR)-α and -γ, in the hepatic circadian clock. Consistent with disturbed hepatic clock gene expression in MLL4 mutant mice, we found that rhythmic fluctuation of hepatic and serum bile acid (BA) levels over the circadian cycle is abolished in MLL4 mutant mice. Our analyses also demonstrate that MLL4 primarily impinges on hepatic BA production among several regulatory pathways to control BA homeostasis. Together, our results provide strong in vivo support for important roles of both MLL3 and MLL4 in similar metabolic pathways. CONCLUSION: Both MLL3 and MLL4 complexes act as major epigenetic regulators of diverse metabolic processes (including circadian control of bile acid homeostasis) and as critical transcriptional coactivators of the circadian TFs, RORs.

Relationship of sodium intake with obesity among Korean children and adolescents: Korea National Health and Nutrition Examination Survey.

We investigated whether dietary and urinary Na is associated with adiposity in Korean children and adolescents (10-18 years), a population with a high salt intake. Study subjects were Korean children and adolescents who participated in the cross-sectional nationally representative Korea National Health and Nutrition Examination Survey (2010-2011). This study used measures of dietary (24-h dietary recall) and urinary Na (Na:creatinine ratio) and three methods to determine obesity (BMI, waist circumference (WC) and total body per cent fat (TBPF)). Higher Na intake was significantly associated with obesity, adjusting for the covariates. Subjects in the highest tertile of urinary Na excretion had a significantly higher OR for higher adiposity compared with those in the lowest tertile (multivariate-adjusted OR 3·13 (95% CI 1·81, 5·50) for BMI, 2·15 (95% CI 1·27, 3·66) for WC and 1·92 (95% CI 1·29, 2·86) for TBPF, respectively). Na intake estimated by the 24-h recall method also showed significant association with adiposity (multivariate-adjusted OR 2·79 (95% CI 1·66, 4·68) for BMI and 2·14 (95% CI 1·25, 3·67) for WC, respectively). The significant associations between Na and adiposity remained significant after additionally adjusting for sugar-sweetened beverage (SSB) consumption. Our results revealed a significant positive association between urinary and dietary Na and adiposity in Korean children and adolescents, independent of SSB consumption.

STAT3 promotes motor neuron differentiation by collaborating with motor neuron-specific LIM complex.

The motor neuron (MN)-hexamer complex consisting of LIM homeobox 3, Islet-1, and nuclear LIM interactor is a key determinant of motor neuron specification and differentiation. To gain insights into the transcriptional network in motor neuron development, we performed a genome-wide ChIP-sequencing analysis and found that the MN-hexamer directly regulates a wide array of motor neuron genes by binding to the HxRE (hexamer response element) shared among the target genes. Interestingly, STAT3-binding motif is highly enriched in the MN-hexamer-bound peaks in addition to the HxRE. We also found that a transcriptionally active form of STAT3 is expressed in embryonic motor neurons and that STAT3 associates with the MN-hexamer, enhancing the transcriptional activity of the MN-hexamer in an upstream signal-dependent manner. Correspondingly, STAT3 was needed for motor neuron differentiation in the developing spinal cord. Together, our studies uncover crucial gene regulatory mechanisms that couple MN-hexamer and STAT-activating extracellular signals to promote motor neuron differentiation in vertebrate spinal cord.